March is the third month of the year in both the Julian and Gregorian calendars. It is the second of seven months to have a length of 31 days. In the Northern Hemisphere, the meteorological beginning of spring occurs on the first day of March. The March equinox on the 20 or 21 marks the astronomical beginning of spring in the Northern Hemisphere and the beginning of autumn in the Southern Hemisphere, where September is the seasonal equivalent of the Northern Hemisphere's March.
The name of March comes from Martius, the first month of the earliest Roman calendar. It was named after Mars, the Roman god of war, and an ancestor of the Roman people through his sons Romulus and Remus. His month Martius was the beginning of the season for warfare, and the festivals held in his honor during the month were mirrored by others in October, when the season for these activities came to a close. Martius remained the first month of the Roman calendar year perhaps as late as 153 BC, and several religious observances in the first half of the month were originally new year's celebrations. Even in late antiquity, Roman mosaics picturing the months sometimes still placed March first.
March 1 began the numbered year in Russia until the end of the 15th century. Great Britain and its colonies continued to use March 25 until 1752, when they finally adopted the Gregorian calendar (the fiscal year in the UK continues to begin on 6 April, initially identical to 25 March in the former Julian calendar). Many other cultures, for example in Iran, or Ethiopia, still celebrate the beginning of the New Year in March.
March is the first month of spring in the Northern Hemisphere (North America, Europe, Asia and part of Africa) and the first month of fall or autumn in the Southern Hemisphere (South America, part of Africa, and Oceania).